Decoratable polyolefin plastics

ABSTRACT

A POLYOLEFIN COMPOSITION COMPRISING (1) ABOUT 35 TO 92 PERCENT OF A CRYSTALLINE POLYMER OF AN A-OLEFIN HAVING 2 TO 8 CARBON ATOMS CONTAINING AT LEAST 90 PERCENT A-OLEFINS UNITS AND AT LEAST PART OF WHICH HAS BEEN CHEMICALLY COMBINED WITH MALEIC ANHYRIDE, (2) 0 TO 30 PERCENT OF A CRYSTALLINE ETHYLENE POLYMER HAVING A DENSITY OF ABOUT 0.91 TO ABOUT 0.97, (3) ABOUT 5 TO 20 PERCENT OF AN ETHYLENE-PROPYLENE COPOLYMER RUBBER CONTAINING 20 TO 80 PERCENT ETHYLENE UNITS, AND (4) ABOUT 3 TO ABOUT 15 PERCENT OF ROSIN. THESE POLYOLEFIN PLASTICS EXHIBIT EXCELLENT ADHESION TO PAINTS, LACQUERS, AND INKS WITHOUT THE NEED FOR EXPENSIVE PRIMERS OR OTHER SURFACE TREATMENTS.

Int. Cl. C09j 3/26 US. Cl. 26027 8 Claims ABSTRACT OF THE DISCLOSURE Apolyolefin composition comprising (1) about 35 to 92 percent of acrystalline polymer of an a-olefin having 2 to 8 carbon atoms containingat least 90 percent u-olefin units and at least part of which has beenchemically combined with maleic anhydride, (2) to 30 percent of acrystalline ethylene polymer having a density of about 0.91 to about0.97, (3) about 5 to 20 percent of an ethylene-propylene copolymerrubber containing 20 to 80 percent ethylene units, and (4) about 3 toabout 15 percent of rosin. These polyolefin plastics exhibit excellentadhesion to paints, lacquers, and inks without the need for expensiveprimers or other surface treatments.

This invention relates to novel decoratable polyolefin compositionshaving improved physical properties. More particularly, this inventionrelates to new and improved polyolefin compositions having excellentadhesion to paints, lacquers and inks Without the need for expensiveprimers or other special surface treatments.

Crystalline polyolefins such as polyethylene and polypropylene arewidely used in many molding and extrusion applications. Usually,whenever colored products are desired, the polyolefin plastics aregenerally melt-blended with an appropriate pigment. Many pigmentedmaterials, however, are unsatisfactory for molding large parts requiringmulti-gated molds. In these cases, especially with the metallic colors,streaks form at the weld lines in the molded piece. Splaying alsoproduces many undesirable effects in pigmented plastics. It is desirabletherefore to be able to paint or decorate the molded polyolefin parts.Unlike many polymers containing polar groups, polyolefins, which arenon-polar, normally show no adhesion to sur- [face coatings and cannotbe painted, printed or decorated without expensive surface treatments.Prior to this invention it has generally been necessary to subject thesurface of the molded or extruded polyolefin part to an expensivesurface treatment such as priming, electronic treating, flaming, acidetching, and the like in order to provide even barely acequate adhesionbetween the polyolefin and paint, ink or other decorative materail.

US. Pat. 3,483,276 describes blends of polypropylene with maleatedpolypropylene. These maleated polyolefin compositions exhibit improvedadhesion to metals, especially aluminum and other types of substrates towhich the polyolefin is applied as a hot melt. It is also disclosed thatthese blends are said to be much more amenable to the application ofdyes, inks, and coating materials generally. It has been discovered thatthe above-described blends have excellent adhesion to many types ofthermosetting enamels but only marginal adhesion at best (and, hencecommercially unacceptable) to non-thermosetting acrylic lacquers. It wasquite surprising, therefore, to discover that this limitation of thecomposition of US. Pat. No. 3,483,276 could be overcome by the additionof natural rosin and that unusually outstanding results would beobtained from polypropylene compositions containing maleatedpolypropylene, rosin, and ethylene-propylene rubber. More broadlystated, it has now been discovered unexpectedly that crystallinepropylene polymers and certain blends of these polymers withpolyethylene when United States Patent 0 ice combined with athree-component modifier system comprising maleated polypropylene,natural rosin and an ethylene-propylene copolymer rubber have excellentadhesion to virtually all decorative materials or surface coatingsincluding non-thermosetting acrylic lacquers. These compositions are thefirst and only polyolefin materials known that can be decorated withacrylic lacquers, as well as other types of paints and inks, withoutpriming or other special surface treatments.

The advantageous effects of the maleated polyolefins and rosin in thisinvention cannot be solely attributed to the presence of carboxyl groupsor carboxyl forming groups in the polymer. Thus, it was found thatacrylic acid graft copolymers of polypropylene containing up to 8%acrylic acid showed virtually no adhesion to paints, either alone orwhen blended with polypropylene. It was also observed that such anacrylic acid graft copolymer showed good adhesion to metals when appliedas a hot melt to the metal, but showed almost no improvement overpolypropylene in adhesion to electroplated metals. In view of the above,it is evident that the advantageous results provided by this inventioncould not have been predicted from the prior art and were completelyunexpected.

It is an object of this invention to provide novel polyolefincompositions that can be painted with both thermosetting enamels andnon-thermosetting lacquers without priming or other surface treatment.

It is another object of this invention to provide new polyolefincompositions having excellent adhesion to all types of surface coatingsapplied in the form of conventional paints, lacquers, inks and byelectro deposition methods.

It is still another object of this invention to provide a method forimproving the adhesion of polyolefin plastics to paints, inks,electro-plated metals and other decorating materials withoutdeleteriously alfecting the physical properties of the polyolefin.

It is still another object of this invention to provide polyolefincompositions which can be joined to themselves, other plastics or tometals by means of conventional adhesives.

Still another object of this invention is to provide polyolefin plasticswhich by virtue of exceptionally tenacious adhesion to glass surfaces,can be used advantageously with glass fiber reinforcement in injectionmolding or as a colaminate with glass fiber mat or fabric.

Other objects are apparent elsewhere in this in this specification.

According to one aspect of this invention there is provided acomposition comprising components 1), (2), (3) and (4) as follows: (1)about 35 to about 92% based upon the weight of the composition of acrystalline polymer of at least one a-olefin having 2-8 carbon atoms orblend of such polymer containing at least 90 weight percent u-olefin atleast part of which is modified with about 0.17 to 10.0 weight percentbased on said crystalline polymer or blend of such polymers of maleicgroups; (2) 0 to about 30 percent based upon the weight of thecomposition of a crystalline ethylene polymer having a density of about0.91 to about 0.97; (3) about 5 to about 20 percent based upon theweight of the composition of an ethylene propylene copolymer rubbercontaining 20-80 weight percent based on said copolymer rubber ofethylene units, and (4) about 3 to about 15 percent based upon theweight of the composition of rosin.

In an especially preferred embodiment of this invention there isprovided a decoratable thermoplastic composition comprising an intimateblend as defined above except that the percentage ranges are (1) about52 to percent, (2) 0 to about 20 percent, (3) about 10 to 15 percent,and (4) about 5 to 13 percent.

The maleated polyolefins useful in the practice of this invention may beprepared by any of the known proce dures as described for example inU.S. Pat. No. 3,414,551, and No. 3,480,580 and U.S. applications Ser.Nos. 519,450, filed Jan. 10, 1966, and Ser. No. 492,849, filed Oct. 4,1965.

The preferred maleated polyolefin useful in the practice of thisinvention is maleated polypropylene, but others of value are derivedfrom crystallizable polyolefins selected from the group comprisingpolyethylene; po-ly(1-butene); ethylene/propylene copolymers;ethylene/l-butene copolymers; ethylene/ l-hexene copolymers; propylene/l-butene copolymers; and poly(4 methyl 1 pentene). Other maleatedpolyolefins may be used but are less desirable either because ofeconomic reasons or because they do not afford optimum results. It ispreferred to use a maleated polyolefin corresponding to the polyolefinto be modified; for example maleated polypropylene is preferred tomodify polypropylene.

Component (1) defined above advantageously contains from about 0.2 toabout 10 weight percent of constituents equivalent to combined maleicanhydride including substituted maleic anhydride, although the preferredpercentage range is about 0.5 to about 5.0 weight percent combinedmaleic anhydride or a derivative thereof. Although maleic anhydried oracid is preferred, itaconic anhydride, citraconic anhydried and fumaricacid can be used to prepare the modified polyolefins useful in thisinvention. A convenient measure of combined maleic anhydride content isthe saponification number of the maleated polymer. The preferredmaleated polyolefins have saponification numbers of about 6 to about 60.The maleated polyolefins may be used alone or may be blended with thecorresponding unmodified polyolefins or mixtures of these with otherpolyolefin materials. It is preferred to utilize the maleatedpolyolefins blended with the corresponding unmodified polyolefins. Themaleated polyolefins may have inherent viscosities as measured inTetralin at 145 C. of from about 0.1 to 2.5. For practical purposes,however, the maleated polyolefins having low inherent viscosities (e.g.$1.0) should be blended with polyolefins of higher inherent viscositiesto produce molding grade plastics. If the maleated polyolefins areblended with unmodified, i.e., nonmaleated olefins polymers, theresulting blends preferably should contain a minimum of 0.17 weightpercent combined maleic anhydride based on the weight of the blend, thisblend being exemplary of component (1) defined above.

The decoratable polyolefin compositions of this invention includecomponents (1) and (2) as described above, of which, preferably, thecrystallizable polyolefin portion is polypropylene, or a copolymer ofpropylene containing at least 90% propylene units or blends of thesepolymers with up to about 30% polyethylene or ethylene-rich (285%)copolymers. The latter may be ethylene/a-olefin, ethylene/vinyl acetate,ethylene/alkyl acrylate or methacrylate, ethylene/acrylic acid and thelike. In general, the crystallizable polyolefins which may beadvantageously modified according to this invention are derived from oneor more olefin monomers having the structure CH CH-R wherein R ishydrogen or a primary or secondary hydrocarbon redical of 1 to 6 carbonatoms and have inherent viscosities in the range of about 0.1 to 3.0.The preferred crystallizable polyolefins are polypropylene, propylene/ethylene copolymers, including block copolymers, poly (l-butene),propylene/l-butene copolymers, and poly (4-methyl-1-pentene). Asoptional component (2) defined above, polyethylene and ethylene-richcopolymers are useful mainly as minor constituents of the overallblends. The polyethylene or ethylene-rich copolymer can have a densityof 0.91 or greater and preferably has a density of 0.95-0.97. The meltindex of the polyethylene should be I 4 about 0.1 to 20; preferably 0.5to 10. Blends of two or more of these crystallizable polyolefins may beused.

Component (3) as defined above includes one or more substantiallyamorphous hydrocarbon elastomers such as ethylene-propylene rubber,ethylene-propylene-diene terpolymer rubber, etc., or mixtures thereof.The tricomponent blends described in U.S. Ser. No. 564,049, filed July11, 1966, and U.S. Pat. No. 3,256,367 are of particular value in thepractice of this invention.

The ethylene-propylene copolymer rubber, component (3) defined above,can be used at concentrations of about 5 to about 20 percent butconcentrations of to are preferred. Suitable ethylene-propylenecopolymer rubber is described in U.S. Pat. No. 3,256,367. Theethylenepropylene rubber should contain to 80 percent by weight ofethylene; preferably the ethylene content should be 30 to 65 percent byweight. The inherent viscosity of the copolymer rubber is measured inTetralin at 145 C. should advantageously be in the range of 1.0 to 3.5;preferably 1.5 to 3.0. The second order transition temperature of thecopolymer rubber should be below C. and preferably below -40 C. It hasalso been found that those copolymer rubbers known as ethylenepropyleneterpolymer rubbers containing minor amounts (up to 10% by weight) ofhydrocarbon diene units or other a-olefin units can also beadvantageously utilized in the practice of this invention.

Rosin which is intended to include rosin derivatives, such as esterifiedrosin or hydrogenated rosin, can be advantageously utilized atconcentrations of about 3% to 15 but the preferred concentrations are 5%to 13%, based on the weight of the composition.

The decoratable polyolefin compositions of this invention may bedecorated with many types of paints, lacquers, and inks. The principalfilm-forming ingredients of these materials may be Versamid amides,cellulose nitrate, ethyl cellulose, cellulose esters, acrylic polymersand copolymers, po1y(vinyl acetate), alkyd resins, urea formaldehyderesins, malamine formaldehyde resins, lacquer maleic resins,rosin-modified bisphenol resins, chlorinated rubber resins, and thelike.

Almost any protective or decorative coating material may be used in thepractice of this invention. The coating materials may be used as clearfinishes or may be pigmented with the usual paint pigments. The coatingsmay be applied by any of the conventional techniques used to applypaints, enamels, lacquers, fiexographic inks, etc. Of particular valuein the practice of this invention are the acrylic type enamelscontaining melamine formaldehyde or urea formaldehyde resins, the epoxycontaining acrylic type coatings, and enamels containing poly (acrylicacid) or poly(methacrylic acid), lacquers based on poly(methylmethacrylate), and the Versamid-based fiexographic inks. (Versamids arediscussed by Golding, Polymers and Resins, D. Van Nostrand Company,Inc., New York, N.Y., p. 294). Also of particular value are thealkyd-amino finishes based on non-oxidizing alkyds and urea-formaldehydeor melamine-formaldehyde.

In addition to their decorability, the modified, decoratable polyolefincompositions of this invention may be bonded by means of many types ofcommercial adhesives. The epoxy adhesives are'especially valuable injoining or forming bonds between the polyolefin compositions of thisinvention and many other types of adherends such as wood, metals, glass,rubbers, plastic materials, paperboard and the like.

In general, the conditions under which the modified polyolefincompositions of U .8. Pat. 3,483,276 are molded affect the adhesion ofthe decorative finish to the molded part. In general, the best resultsare obtained by injection molding the compositions using high melttemperatures and slow injection or fill rates. However, moldingconditions are not critical to the adhesion between the decorativefinish and the molded article formed from the cornpositions of thisinvention. In some cases, however, immediately after forming a moldedpart, a freshly decorated surface may show unsatisfactory adhesioninitially, but will show excellent adhesion after aging at ordinarytemperatures for two to three days. In some cases, especially when thedecoratable polyolefin composition contains less than about 0.5 weightpercent combined maleic anhydride or less than 7 percent rosin, theinitial adhesion of the molded parts to the decorative finish may beimproved by preconditioning the molded part by heating it at atemperature of about 5 C. below the softening point for 15 to 30minutes. None of these factors, however, should be regarded as limitingthe invention. They are presented merely to facilitate the practice ofthe invention.

Any of the conventional melt blending techniques, such as the use of aBanbury mixer, compounding extruder, mixing rolls, and the like, may beused to blend the maleated polyolefins and rosin with the desiredcrystallizable polyolefins and elastomeric hydrocarbon polymers, i.e.,components (1), (2), (3) and (4) as described above.

(tor sample) Sap. No.=(

As stated previously, the concentration of the maleated polyolefin to beused in the blend will be determined by the saponification number (orconcentration of combined maleic anhydride) of the maleated polyolefinand the desired physical properties of the blend. Any desiredcombination or proportions of the maleated polyolefins and theunmodified polymers may be used in accordance with this inventionprovided the resulting composition contains 'at least 0.17% by weight ofcombined maleic anhydride based on the weight of the crystallizablepolymer or blend of such polymers.

The decoratable polyolefin compositions of this invention may containantioxidants, fire retardants, weathering inhibitors, pigments,nucleating agents, metal deactivators, fillers such as talc, carbonblack and the like, reinforcing agents such as glass fibers, asbestos,and the like, functional polymeric additives, and other conventionalpolyolefin additives.

This invention may be more fully understood by reference to thefollowing illustrative examples, which are in: tended to describecertain embodiments of this invention. Parts and percentages are byweight and temperatures are in degrees centigrade unless otherwisespecified.

All inherent viscosities (I.V.) are determined by measuring the flowtime in a Schulken-Sparks viscometer (J. Polymer Science, 26, 227-230,1957) of a 0.25% solution of the polymer in Tetralin solvent at 145C.

The melt flow rates are determined in accordance with ASTM D-1238-62T bymeans of an extrusion plastometer using condition L (230 C.; 2.16 kg.load).

Density is determined using a density gradient tube.

The adhesion of the coatings to the decoratable composition surface isdetermined by the conventional cellophane tape adhesion test in which acrosshatched pattern is scored at about Aa-inch intervals in thecoating. A strip of adhesive cellophane tape (Minnesota Mining andManufacturing Company) is then applied with moderate finger pressureacross the area, after which the tape is removed by grasping it andpulling it rapidly and evenly from the surface. If no paint or ink isremoved from the specimen after this treatment, the adhesion of thecoating to the specimen surface is classed as excellent. If paint orother coating is stripped away from the specimen only in the cuts orgrooves of the crosshatched area, the adhesion is classed as good. Ifthe coating is stripped away from the crosshatched area, but is notremoved when the test is applied to a smooth area of the specimen theadhesion is classed as fair. If the coating strips from the specimenwhen the test is applied to a smooth area, the adhesion is poor.

1 One method for the determination of the saponification number of themaleated polyolefins which is employed for the examples below is asfollows:

Approximately 4 g. of sample is weighed into a 500 ml. alkali-resistantErlenmeyer flask, and 100 ml. of distilled xylene is added. The mixtureis heated under a reflux condenser for one hour and then cooled to F. orlower. From a buret 30 ml. of standardized 0.10 N potassium hydroxidesolution in ethyl alcohol is added. The solution is heated under refluxfor 45 min. and then cooled. From a buret standardized 0.10 N aceticacid in xylene is added until the mixture is acid to phenolphthalein.Then, at least 1 ml. of excess acetic acid solution is added. Thesolution is reheated under reflux for 15 min. and removed from the heat.After the addition of 5 ml. of water, the solution is titrated to afaint pink end point with 0.10 N potassium hydroxide solution in ethylalcohol.

A blank is run in this manner using the same amounts of reagents and thesame heating schedule.

(for blank) g. Sample EXAMPLE 1 In a Banbury mixer are blended together65 parts of polypropylene having a melt flow rate of 4.5, 10 parts ofmaleated polypropylene having an inherent viscosity of 0.2 and asaponification number of 41, 10 parts of rosin (water white grade) and15 parts of Enjay Vistalon 404 ethylene-propylene copolymer rubber.Specimens of this blend are injection molded on an Ankerwerk machineusing a melt temperature of 450 F. Specimens are washed with detergent,dried and sprayed with Du Pont Dulux enamel. The painted specimens areair dried, then baked at 250 F. for 30 min. The specimens are allowed tocool to room temperature and the adhesion of the enamel is testedimmediately. The adhesion is excellent as determined by the cellophanetape test.

When Du Pont Lucite acrylic lacquer is used instead of the thermosettingenamel and the coating is cured for 1 hr. instead of 30 min., excellentadhesion to the surface is again observed.

Similar results are obtained when amorphousethylenepropylene-methylenenorborene terpolymer rubber is used in placeof the ethylene-propylene rubber above. When the maleated polypropyleneis omitted from the above blends, the plastics show poor adhesion to thecoatings.

Example A (for comparison) Maleated polypropylene (7 parts) having aninherent viscosity of 0.2 and a saponification number of 41 is meltblended in a Banbury mixer with stereoregular polypropylene (93 parts)having a melt flow rate of 4.5. The resulting blend is cooled,granulated, and then injection molded on an Ankerwerk screw-ram moldingmachine using a melt temperature of 450 F. and a slow fill rate. Themolded specimens are washed in detergene (note that it is important thatno silicone-type mold release agents be used during molding ofspecimens), dried, and then spray painted using a thermosettingacrylic/melamineformaldehyde type enamel (e.g., Rinshed-Mason Co.,Comanche Red interior enamel). The freshly painted specimens are airdried, then baked at 25 0 F. for 30 minutes. After aging at roomtemperature (23 C.) for 48 hours, the adhesion of the paint to theplastic is excellent as shown by the cellophane tape test ofcross-hatched specimens. Excellent adhesion is also found on similarspecimens treated in boiling water for 30 minutes.

When Du Pont Lucite acrylic lacquer is used instead of the thermosettingenamel and the coating is cured at 250 F. for 1 hr. the coating does notadhere to the molded specimen.

When the concentration of the maleated polypropylene is reduced to 3.5%the adhesion of the thermosetting enamel to a molded specimen of theblend is very poor; ehe adhesion of acrylic lacquer is nil. When themaleated polypropylene is omitted altogether, the paint adhesion is nilin all cases.

Example B (for comparison) The procedures of Example 1 are repeated, butthe rosin is omitted. The adhesion of the thermosetting enamel is good,but the adhesion of acrylic lacquer is very poor.

Example C (for comparison) The procedures of Example 1 are repeated butthe ethylene-propylene copolymer rubber is omitted. The ad hesion of thethermosetting enamel to the plastic is good but the adhesion of theacrylic lacquer is very poor.

EXAMPLES 2-7 The effects of variations in blend composition on theadhesion of thermosetting enamel are shown in the following table. Thematerials and procedures described in Example 1 are used. Note that thesecond and third columns list amounts of component (1), the fourthcolumn lists amounts of component (3), and the third column listsamounts of component (4) of the decoratable polyolefin compositions ofthis invention. Component (2) is optional and not included in thefollowing table.

I Saponification No. 41;

b Water-white grade.

' Enjay Vistalon 404 ethylene/propylene copolymer rubber (EPR). Du PontDulux enamel.

Example D (for comparison) Maleated polypropylene having an inherentviscosity of 1.4 and a saponification number of 6 is injection moldedusing a melt temperature of 400 F. and a slow fill rate. The moldedspecimens are washed, dried, and painted. Specimens painted with Du PontDulux thermosetting enamel are baked at 250 F. for 30 min., whilespecimens painted with Du Pont Lucite acrylic lacquer are baked at 250F. for 1 hr. The adhesion of the thermosetting enamel to the polymer isgood but the acrylic lacquer showed poor adhesion. No improvement in theadhesion is evident after the coated specimens have aged at roomtemperature for 3 days.

EXAMPLE 8 The maleated polypropylene (75 parts) described in Example Dis blended in a Banbury mixer with 10 parts rosin and parts EnjayVistalon 404 ethylene/ propylene copolymer rubber. Injection moldedspecimens are washed, dried, and painted. Specimens painted with Du PontDulux thermosetting enamel are baked at 250 F. for 30 min., whilespecimens painted with Du Pont Lucite acrylic lacquer are baked at 250F. for 1 hr. The specimens are allowed to stand at room temperature for3 days, then are tested. The adhesion of both the acrylic lacquer andthe thermosetting enamel is excellent.

EXAMPLE 9 The procedures of Example 1 are followed, but 12.5 parts ofmaleated poly(l-butene) having an inherent viscosity of 0.5 and asaponification number of 32 are used instead of the maleatedpolypropylene, and 15 parts of Enjay Chemical Co., Vistalon 3509ethylene-propylene- 8 methylenenorbornene terpolymer rubber are usedinstead of the Vistalon 404 rubber. The adhesion of both thermosettingenamel and acrylic lacquer to injection molded specimens of this blendis excellent.

EXAMPLE 10 The procedures of Example 1 are followed to prepare, mold,and paint specimens of a blend composed of 55 parts of polypropylene, 15parts of polyethylene having a density of 0.958 and a melt index of 2,10 parts maleated polypropylene, 10 parts rosin, and 15 parts Vistalon404 ethylene/propylene copolymer rubber. The adhesion of Du Pont Duluxenamel and of Du Pont Lucite acrylic lacquer to the injection moldedspecimens is excellent. Similar results are obtained when theproportions of polypropylene and polyethylene are changed to 45.5 partsand 19.5 parts, respectively.

EXAMPLE 11 Two tensile test specimens from each of the blends fromExamples 1, 2 and 5 are bonded together by means of lap joints using anepoxy adhesive (U.S. Plywood Corp., epoxy glue). After 24 hours, thebonds are tested in tension using an Instron Tensile Tester. In eachcase there is no rupture of the bond before the plastic yields or breaksoutside the bonded area. When an attempt is made to bond unmodifiedpolypropylene surfaces no adhesion between the plastic surfaces and theepoxy adhesive is observed.

EXAMPLE 12 A blend of 65 parts of polypropylene (melt flow rate 3.1,density 0.912), 10 parts maleated polypropylene (saponification number41), 10 parts of rosin, and 15 parts Enjay Vistalon 404ethylene-propylene copolymer rubber are blended in a compoundingextruder and extruded into film of 1.5 mil. thickness. The film isprinted with a Versamid-based Flexotuf flexographic ink and allowed todry for 24 hours. The adhesion to the plastic is excellent. Similarresults are obtained when the ink is dried for 5 minutes under aninfrared lamp (General Electric, 250 w.) at a distance of 18 inches.

EXAMPLE 13 The procedure of Example 12 is followed, except that thethickness of the extruded film is 10 mils. A laminated composite isformed by stacking alternate layers of film and glass fabric or cloth.Four layers of film and three layers of glass cloth are used. Thestacked assembly is pressed at 450 F. between platens at a pressure of1,000 p.s.i. for 1 min. The pressure is maintained while the platens andcomposite are cooled to room temperature. The laminated compositecontaining 28% glass has a tensile break strength of 7400 p.s.i. and amodulus in flexuse of 375,000 p.s.i. A laminated composition of similarstructure, using unmodified polypropylene film, has a tensile yieldstrength of 7,200 p.s.i., tensile break strength of 2600 p.s.i. and amodulus in fiexure of 297,000 p.s.i.

EXAMPLE 14 To a compounding extruder is fed a mixture of 30 parts byweight /r-inch glass fibers and 70 parts by weight of a blend having thecomposition described in Example 1. The extrudate is cooled in chilledwater and chopped into pellets Va-inch in diameter and %-inch long. Thepellets are then fed to a Van Dorn injection molding machine to formarticles having exceptionally high strength. When the specimens arebroken, examination of the broken ends of the specimens by means of ascanning electron microscope shows that glass fibers are coated withpolymer. The glass fibers revealed in the broken ends of specimens fromblends of glass fibers with unmodified polypropylene are not coated withpolymer, but slip cleanly from the polymer matrix, leaving a clean,cylindrically shaped hole. The glass reinforcement did not detract fromthe aflim'ty of the modified polypropylene blend for thermosettingenamel or acrylic lacquer. Similarly, fillers such as talc, titania,alumina, or asbestos do not deleteriously affect the paint to plasticsurface adhesion when blended in concentrations up to about 40-5 byweight with the modified polypropylene blends.

Example E (for comparison) EXAMPLE 15 The procedure of Example A isfollowed to compound and mold a blend of maleated polypropylene (7.5parts) having an inherent viscosity of 0.3 and a sapom'fication numberof 58, stereoregular polypropylene (59 parts) having a melt flow rate of4.5, linear polyethylene (15 parts) having a density of 0.96 and a meltindex of 1.0, amorphous Enjay Vistalon 404 ethylene-propylene rubber (11parts) and rosin (water white grade, 7.5 parts). The molded specimensare spray painted with a thermosetting acrylic/melamine-formaldehydetype enamel and with an acrylic lacquer. The freshly painted specimensare air dried, then baked at 250 F. for one hour. After cooling to roomtemperature (23 C.), the adhesion of both the enamel and the lacquer tothe plastic is excellent as shown by the cellophane tape test oncrosshatched specimens.

EXAMPLES 16-21 The procedure of Example 15 is followed using variouscombinations of stereoregular polypropylene (melt flow rate 4.5),maleated polypropylene (saponification number of 41), linearpolyethylene (melt index 0.7), rosin, and Enjay Vistalon 404ethylene-propylene rubber. The results are shown in the table below.

- 10 ing an inherent viscosity of 1.8 instead of polypropylene. Thepaint-to-plastic adhesion is excellent.

The table below illustrates the physical properties of the paintableblends of this invention. Thus, the compounded blends of Examples 2, l7,and 19 are injection molded into test specimens on an Ankerwerk moldingmachine and are tested in accordance with the ASTM procedures indicatedin the table.

TABLE III Composition, Example No.

Property Testmethod (2) (17) (19) Flow rate, g./10 min ASTM D1238 13 1412 Tensile strength:

At yield,p.s.i ASTM D638 2, 600 2, 700 At break, p.s.i ASTM D638 2, 4003, 100 2, 400 Stifinessinflexurapsi ASTM D747 83,000 99,000 77,000Notched Izod impact strength at 23 0., ft.-lb./in. of notch ASTM D256 1.2 1. I 1. 9 Hardness:

Rockwell (R).. ASTM D785 64 36 Shore Durometer (D) ASTM D1706 65 Whenthe compositions in question are reinforced with A-inch glass fibers(such as Johns-Manville Type CS- 308) to give composites containing 20%glass, the tensile strengths of the compositions are increasedthree-fold and the stifinesses are increased four-fold. These glassfiber composites also show paint adhesion comparable to the originalnonreinforced compositions.

The polyolefin compositions of this invention are thus eminentlysuitable for manufacturing automotive parts which can be painteddirectly and which can be bonded to metal with common industrialadhesives such as the epoxy adhesives. The compositions of thisinvention may also be combined with glass fiber matting or fabric toform laminated sheets which can then be thermoformed into various shapessuch as automobile door shells, door liners, fender skirts, hoods, andother automobile body parts. The parts thus formed can then be paintedor decorated, 'without priming or other surface treatments other thancleaning, using the same paints used to decorate TABLE II Example No 1617 18 19 20 21 Composition, percent:

Polypropylene 69 64 54 60 55 50 Maleated polypropylene 7. 5 7. 5 7. 5 7.5 7. 5 7. 6 Polyethylene- 5 10 20 10 15 20 R 7.5 7.5 7.5 7.5 7.5 7.5 1111 11 15 15 15 Excellent Excellent Excellent Excellent ExcellentExcellent Lacquer Fair Excellent Excellent Excellent Excellent ExcellentEXAMPLE 22 the metal parts of the automobile. The compositions of Theprocedure of Example 8 is followed using a maleated 92/8propylene/ethylene block copolymer having an inherent viscosity of 1.8and a saponification number of 8 instead of the maleated polypropylene.The adhesion of both the thermosetting enamel and the arcylic lacquer tothe molded specimens is excellent.

EXAMPLE 24 The procedure of Example 1 is followed using acostereosymmetric 97/3 propylene/ l-butene copolymer havthis inventionmay be injection molded, extruded, vacuum formed, blow molded, welded,heat sealed, machined, and processed by other conventional techniquesnormally used on polyolefin plastics.

It is desirable to incorporate antioxidants and, when needed, weatheringinhibitors into the compositions of this invention, since the presenceof carboxylic acid groups tends to lower the oxidative stability ofpolyolefins. Any of the conventional polyolefin stabilizers aregenerally satisfactory, for example, pentaerythritol tetrakis(3,5-ditert-butyl 4-hydnoxyhydrocinnamate); l,3,5-trimethyl-2,4, 6tri(3,5 di-tert-butyl-4-hydroxybenzyl)benzene; octadecyl 3,5di-tert-butyl-4-hydroxydrocinnamate; and 2,6- bis(1methylheptadecyl)-p-cresol. These stabilizers are especially beneficialwhen used in combination with dilauryl 3,3'-thiodipropionate and/ordistearyl 3,3'-thiodipropionate.

Although the invention has been described in considerable detail withreference to certain preferred embodiments thereof, it will beunderstood that variations and modifications can be effected withoutdeparting from the spirit and scope of the invention.

We claim:

1. A composition comprising components (1), (2), and (3) as follows:

(1) about 35 to about 92 percent, based upon the Weight of thecomposition, of a crystalline propylene polymer containing at least 90weight percent propylene at least part of which is modified with about0.17 to 10 Weight percent based on said crystalline propylene polymer ofmaleic groups;

(2) about 5 to about 20 percent, based upon the weight of thecomposition, of an ethylene-propylene copolymer rubber containing 20 to80 weight percent based on said copolymer rubber of ethylene units; and

(3) about 3 to about 15 percent, based upon the weight of thecomposition, of rosin.

2. The composition of claim 1 containing (4) up to about 30% based uponthe weight of the composition, of a crystalline ethylene polymer havinga density of about 0.91 to about 0.97.

3. The composition of claim 2 wherein the percentages of components (1),(2), (3), and (4) are as follows:

(1) about 52 to 85 percent;

(2) about to percent;

(3) about 5 to 13 percent; and

(4) up to about percent.

4. The composition of claim 2 wherein the crystalline propylene polymeris polypropylene, and the crystalline ethylene polymer is linearpolyethylene.

5. The composition of claim 2 wherein the crystalline propylene polymeris polypropylene, the crystalline ethylene polymer is linearpolyethylene, and the ethylene-pro- 12' pylene copolymer rubber isethylene-propylene-methylenenorbornene terpolymer.

6. The composition of claim 2 wherein the crystalline propylene polymeris propylene/ethylene block copolymer, and the crystalline ethylenepolymer is ethylene/ l-hexene copolymer.

7. The composition of claim 2 wherein the crystalline propylene polymeris propylene/ethylene block copolymer, the crystalline ethylene polymeris ethylene/ l-hexene copolymer, and the ethylene-propylene copolymerrubber is ethylene-propylene-methylenenorbornene terpolymer.

8. The composition of claim 2 wherein the crystalline propylene polymeris propylene/ l-butene copolymer.

References Cited UNITED STATES PATENTS 3,697,465 10/1972 Joyner et al260-27 EV 3,542,714 11/1970 Metters 260-24 3,220,966 11/ 1965 Flanagan260-27 3,483,276 12/1969 Mahlman 260-848 3,343,582 9/1967 Hines et a1.260-889 3,066,132 11/1962 Edmonds 260-882 DONALD E. CZAIA, PrimaryExaminer W. E. PARKER, Assistant Examiner

